Modelos de inferência de alterações ambientais baseados em diatomáceas (Bacillariophyta) de sedimentos das lagoas dos Açores

Dissertação de Mestrado em Biodiversidade e Ecologia Insular.As alterações ambientais locais e globais podem afectar a qualidade ecológica dos lagos. Na ausência de dados históricos, a detecção e quantificação destas alterações podem ser reveladas por técnicas paleolimnológicas. Os sedimentos lacustres têm sido utilizados cada vez mais nos últimos anos para inferir flutuações nas condições ambientais do passado, e vários estudos que abrangem diversas escalas, locais e temporais, têm mostrado a importância dos lagos como arquivos paleoclimáticos e ecológicos. Dos vários depósitos biológicos preservados nos sedimentos lacustres, as diatomáceas constituem indicadores paleoecológicos úteis, principalmente pela sua grande abundância, as suas frústulas de sílica encontram-se bem preservadas e pela elevada diversidade específica. De modo a desenvolver modelos de inferência para as variáveis ambientais a partir das diatomáceas dos sedimentos, 40 lagos, distribuídos pelas ilhas dos Açores, foram amostrados utilizando um corer gravimétrico e diversas variáveis ambientais foram medidas, entre as quais, variáveis hidromorfológicas, físico-químicas e variáveis de impacte. Identificaram-se 207 taxa de diatomáceas, distribuídos por 55 géneros. Realizaram-se análises multivariadas (PCA, ANOSIM, nMDS, SIMPER, DistLM) para analisar os conjuntos de diatomáceas dos sedimentos superficiais e para relacionar estes com as condições ecológicas e ambientais. Verificou-se que existem diferenças estatisticamente significativas na composição taxonómica para o grupo “Tipologia” (R = 0,449; p = 0,001), lagoas profundas e pouco profundas. As espécies que mais contribuem para a dissimilaridade entre as tipologias de lagoas são Aulacoseira ambigua, Asterionella formosa, A. granulata, características de lagoas profundas e Stauroforma exiguiformis, Tabellaria flocculosa morfo 1 e Brachysira brebissonii, características de lagoas pouco profundas. O dbRDA ilustra como as comunidades de diatomáceas se encontram separadas pela tipologia das lagoas, sendo as variáveis que mais contribuem para essa separação a condutividade e o pH e variáveis indicadoras do estado trófico, clorofila a e fósforo total. As variáveis que apresentaram maior correlação com as diatomáceas foram usadas para desenvolver funções de transferência baseadas no Weighted Averaging (WA) e Weighted Averaging Partial Least Squares (WA-PLS), modelos de calibração e regressão. De uma forma geral o método WA classical deshrinking foi aquele que apresentou melhor desempenho para as variáveis pH, condutividade, fósforo total, profundidade máxima, clorofila a, sílica e temperatura média do ar no mês de Julho. Os valores de predição por Jack-Knife obtidos para estas variáveis são bastante elevados (R2 Jack-Knife de 0,829; 0,797; 0,822; 0,848; 0,579; 0,529 e 0,485, respectivamente) e os erros de predição (RMSEP) e os enviesamentos são reduzidos. As funções de transferência revelam-se de uma importância extrema, pois permitem reconstruir quantitativamente as últimas condições ambientais, proporcionam ferramentas para a caracterização de tipologias de lagos, permitem definir as condições de referência ecológica e química e permitem avaliar o desvio a partir dos estados de referência. O reconhecimento do impacte que as alterações ambientais passadas exerceram sobre os ecossistemas pode contribuir significativamente para a previsão de alterações futuras resultantes de alterações ambientais locais e globais.ABSTRACT: Local and global environmental changes can affect ecological quality of lakes. In the absence of historical data the detection and quantification of these changes can be reveled by paleolimnological approaches. Lake sediments have been used increasingly in recent years to infer past fluctuations in environmental conditions and several studies covering several local and temporal scales have shown the importance of lakes as paleoclimate and ecological archives. Of the range of biological remains preserved in lake sediments, diatoms are useful paleoecological indicators mostly because their wide distribution well preserved silicate frustules, high indicator values and high species diversity. In order to develop inference models for environmental variables from diatom assemblages in sediments, 40 lakes distributed throughout Azorean islands were sampled using a gravimetric corer and several environmental variables were measured. 207 taxa, spread over 55 genera were identified. Multivariate analyses (PCA, ANOSIM, nMDS, SIMPER, DistLM) were used in order to analyze the diatoms assemblages in the surface sediments and to relate them with the ecological and environmental conditions. Was verified that there are statistically significant differences in taxonomic composition for the “Typology” group (R = 0,449, p = 0,001), deep and shallow lakes. The species that most contributed to the dissimilarity between lakes typology were, Aulacoseira ambigua, Alterionella formosa, A. granulata, species mostly found in deep lakes and Stauroforma exiguiformis Tabellaria flocculosa morfo 1 and Brachysira brebissonii, species mostly found in shallow lakes. The dbRDA illustrates how diatom communities are separated by lakes typology. The variables conductivity and pH and the indicator variables of trophic state, chlorophyll a and total phosphorous were those that most contributed to this separation. The variables with the highest correlation with diatoms assemblages were used to develop transfer functions based in Weighted Averaging (WA) and Weighted Averaging Partial Least Square (WA-PLS), regression and calibration models. In general, the WA classical deshrinking method presented the best performance for pH, conductivity, total phosphorous, maximum depth, chlorophyll a, silica and average air temperature in July. The prediction values obtained by Jack-Knife for those variables are quite high (R2 Jack-Knife de 0,829; 0,797; 0,822; 0,848; 0,579; 0,529 e 0,485, respectively), and errors of prediction (RMSEP) and bias values are reduced. Transfer functions allow to reconstruct quantitatively past environmental conditions, provide tools for characterizing lake types, define the ecological and chemical reference conditions and allow to evaluate the deviation from the reference state. The recognition of the impact that past environmental changes exerted on the ecosystem can contribute significantly to the prediction of future changes resulting from local and global environmental changes

Interplay between productivity and regional species pool determines community assembly in aquatic microcosms

The relative importance of deterministic and neutral processes in shaping assembly of communities remains controversial, partly due to inconsistencies between theoretical, empirical, and experimental studies. We investigate the interplay between local (productivity) and regional (size of species pool) assembly mechanisms in communities of phytoplankton and zooplankton in 72 experimental microcosms. Local environmental conditions were manipulated by varying the level of nutrients in the water (ambient, low, high). The size of regional species pool colonizing each microcosm was manipulated by mixing phytoplankton and zooplankton species from different numbers of source ponds (n = 2, 4, 8 and 16). Our results show that local communities assembled differently depending on the numbers of sources available for colonization. Microcosms with larger species pools supported greater numbers of species. In contrast, the effects of productivity led to different results across trophic groups. Phytoplankton communities were, on average, more diverse on more productive treatments, while zooplankton communities were more diverse under less productive treatments. Phytoplankton and zooplankton communities responded to both sources of variation, although the size of species pool was a better predictor of communities’ composition than the local effects of productivity. These results reinforce the view that community assembly is influenced by the interplay of both local and regional drivers but that the relative importance of these factors varies with trophic groups.Research by CLP, MGM, and MBA was supported through the Integrated Program of IC&DT (1/SAESCTN/ALENT-07-0224-FEDER-001755). MGM acknowledges support by a Marie Curie Intra-European Fellowship within the 7th European Community Framework Programme (FORECOMM) and TrophicResponse-Trophic responses to macroecological gradients funded by FCT (PTDC/BIA-BIC/0352/2014). CLP acknowledges support by the Portuguese Science and Technology Foundation (FCT) through Ph.D. studentship (SFRH/BD/102020/2014). MBA acknowledges support by a Spanish Ministry of Economy and Competitiveness project (CGL2015-68438-P)

Fine-tuning biodiversity assessments: A framework to pair eDNA metabarcoding and morphological approaches

1. Accurate quantification of biodiversity can be demanding and expensive. Although environmental DNA (eDNA) metabarcoding can facilitate biodiversity assessments through non-invasive, cost-efficient, and rapid surveys, the approach struggles to outperform traditional morphological approaches in providing reliable quantitative estimates for surveyed species (e.g., abundance and biomass).2. We present an integrated methodology for improving biodiversity surveys that pairs eDNA metabarcoding with morphological data, following a series of taxonomic and geographic filters. We demonstrate its power by applying it to a new spatiotemporal dataset generated on an Iberian-wide distributed aquatic mesocosm infrastructure that spans a wide biogeographic gradient.3. By building upon the strengths that these two approaches offer, our framework improved taxonomic resolution for 30% of the taxa and enabled species’ traits (e.g., body-size) and abundance to be assigned to 85% of the taxa in hybrid datasets.4. These results indicate that eDNA-based assessments can complement, but not always replace, conventional approaches. Integrating conventional and modern eDNA metabarcoding approaches, already available in the ecologist’s toolbox, will greatly enhance biodiversity assessments.This work was supported by the Portuguese Science and Technology Foundation (FCT) through the scientific projects TrophicResponses - Trophic responses to macroecological gradients (PTDC/BIA-BIC/0352/2014), and StateShifts - Predicting state shifts in energetic food webs under climate change (PTDC/AAG-MAA/3764/2014). This work was also funded by FEDER funds through the COMPETE 2020 Programme and National Funds through FCT under the project number POCI-01-0145-FEDER-007688 and PTDC/CTA-AMB/30793/2017 (AdaptAlentejo – Predicting ecosystem-level responses to climate change). The Iberian Pond network has received funding from the European Union’s Horizon 2020 research and innovation programme under grant Nos 731065 (AQUACOSM) and 871081 (AQUACOSM-plus). CLP acknowledges support by the Portuguese Science and Technology Foundation (FCT) through PhD studentship (SFRH/BD/102020/2014).We acknowledge support of the publication fee by the CSIC Open Access Publication Support Initiative through its Unit of Information Resources for Research (URICI).Peer reviewe

Fine-tuning biodiversity assessments: A framework to pair eDNA metabarcoding and morphological approaches

Accurate quantification of biodiversity can be demanding and expensive. Although environmental DNA (eDNA) metabarcoding can facilitate biodiversity assessments through non-invasive, cost-efficient and rapid surveys, the approach struggles to outperform traditional morphological approaches in providing reliable quantitative estimates for surveyed species (e.g. abundance and biomass). We present an integrated methodology for improving biodiversity surveys that pairs eDNA metabarcoding with morphological data, following a series of taxonomic and geographical filters. We demonstrate its power by applying it to a new spatiotemporal dataset generated on an Iberian-wide distributed aquatic mesocosm infrastructure that spans a wide biogeographical gradient. By building upon the strengths that these two approaches offer, our framework improved taxonomic resolution for 30% of the taxa and enabled species’ traits (e.g. body size) and abundance to be assigned to 85% of the taxa in hybrid datasets. These results indicate that eDNA-based assessments can complement, but not always replace, conventional approaches. Integrating conventional and modern eDNA metabarcoding approaches, already available in the ecologist's toolbox, will greatly enhance biodiversity assessments

Divergent trophic responses to biogeographic and environmental gradients

Following environmental changes, communities disassemble and reassemble in seemingly unpredictable ways. Whether species respond to such changes individualistically or collectively (e.g. as functional groups) is still unclear. To address this question, we used an extensive new dataset for the lake communities in the Azores' archipelago to test whether: 1) individual species respond concordantly within trophic groups; 2) trophic groups respond concordantly to biogeographic and environmental gradients. Spatial concordance in individual species distributions within trophic groups was always greater than expected by chance. In contrast, trophic groups varied non-concordantly along biogeographic and environmental gradients revealing idiosyncratic responses to them. Whether communities respond individualistically to environmental gradients thus depends on the functional resolution of the data. Our study challenges the view that modelling environmental change effects on biodiversity always requires an individualist approach. Instead, it finds support for the longstanding idea that communities might be modelled as a cohort if the functional resolution is appropriate.Peer Reviewe

Divergent trophic responses to biogeographic and environmental gradients

Following environmental changes, communities disassemble and reassemble in seemingly unpredictable ways. Whether species respond to such changes individualistically or collectively (e.g. as functional groups) is still unclear. To address this question, we used an extensive new dataset for the lake communities in the Azores' archipelago to test whether: 1) individual species respond concordantly within trophic groups; 2) trophic groups respond concordantly to biogeographic and environmental gradients. Spatial concordance in individual species distributions within trophic groups was always greater than expected by chance. In contrast, trophic groups varied non-concordantly along biogeographic and environmental gradients revealing idiosyncratic responses to them. Whether communities respond individualistically to environmental gradients thus depends on the functional resolution of the data. Our study challenges the view that modelling environmental change effects on biodiversity always requires an individualist approach. Instead, it finds support for the longstanding idea that communities might be modelled as a cohort if the functional resolution is appropriate.Peer Reviewe

Data from: Divergent trophic responses to biogeographic and environmental gradients

Following environmental changes, communities disassemble and reassemble in seemingly unpredictable ways. Whether species respond to such changes individualistically or collectively (e.g. as functional groups) is still unclear. To address this question, we used an extensive new dataset for the lake communities in the Azores' archipelago to test whether: 1) individual species respond concordantly within trophic groups; 2) trophic groups respond concordantly to biogeographic and environmental gradients. Spatial concordance in individual species distributions within trophic groups was always greater than expected by chance. In contrast, trophic groups varied non-concordantly along biogeographic and environmental gradients revealing idiosyncratic responses to them. Whether communities respond individualistically to environmental gradients thus depends on the functional resolution of the data. Our study challenges the view that modelling environmental change effects on biodiversity always requires an individualist approach. Instead, it finds support for the longstanding idea that communities might be modelled as a cohort if the functional resolution is appropriate

Resveratrol-loaded lipid nanocarriers are internalized by endocytosis in yeast

Different positive pharmacological effects have been attributed to the natural product resveratrol (RSV), including antioxidant, antiaging, and cancer chemopreventive properties. However, its low bioavailability and rapid metabolic degradation has led to the suspicion that many of the biological activities of this compound observed in vitro may not be attainable in humans. To improve its bioavailability and pharmacokinetic profile, attempts have been made to encapsulate RSV into lipid-based nanocarrier systems. Here, the dioctadecyldimethylammonium bromide (DODAB):monoolein (MO) liposomal system (1:2) loaded with RSV revealed appropriate characteristics for drug release purposes: reduced size for cellular uptake (157 ± 23 nm), stability up to 80 days, positive surface charge ( +40 mV), and a controlled biphasic release of RSV from the lipid nanocarriers over a period of almost 50 h at pH 5.0 and 7.4. Moreover, the encapsulation efficiency of the nanocarrier ranged from 70% to 92% and its RSV loading capacity from 9% to 14%, when [RSV] was between 100 and 200 M. The partition coefficient (Kp) of RSV between lipid and aqueous phase was log Kp = 3.37 ± 0.10, suggesting moderate to high lipophilicity of this natural compound and reinforcing the lipid nanocarriers suitability for RSV incorporation. The thermodynamic parameters of RSV partitioning in the lipid nanocarriers at 37 °C (H = 43.76 ± 5.68 kJ mol1; S = 0.20 ± 0.005 kJ mol1; and G = 18.46 ± 3.48 kJ mol1) reflected the spontaneity of the process and the establishment of hydrophobic interactions. The cellular uptake mechanism of the RSV-loaded nanocarriers labeled with the lipophilic fluorescent probe 1,6-diphenyl-1,3,5-hexatriene (DPH) was studied in the eukaryotic model system Saccharomyces cerevisiae. Thirty minutes after incubation, yeast cells readily internalized nanocarriers and the spots of blue fluorescence of DPH clustered around the central vacuole in lipid droplets colocalized with the green fluorescence of the lipophilic endocytosis probe FM1-43. Subsequent studies with the endocytosis defective yeast deletion mutant (end3) and with the endocytosis inhibitor methyl--cyclodextrin supported the involvement of an endocytic pathway. This novel nanotechnology approach opens good perspectives for medical applications.This work was supported by the Portuguese Foundation for Science and Technology (FCT) in the framework of the strategic funding UID/BIA/04050/2019, UID/FIS/04650/ 2019 and UID/AGR/04033/2019; and by the projects PTDCBIA-FBT/28165/2017 (POCI-01-0145-FEDER-028165), PTDC/BIA-FBT/30341/2017 (POCI-01-0145-FEDER030341) and PTDC/NAN-MAT/32651/2017 (POCI-010145-FEDER-032651). C.S.P. is a recipient of the PD/BD/ 128032/2016 fellowship funded by FCT under the scope of the Doctoral Program on Applied and Environmental Microbiology (DP_AEM). We thank J. Demaître (Faculty of Pharmaceutical Sciences, University of Ghent) for her contribution to HSA binding assays.info:eu-repo/semantics/publishedVersio